The In-Space Propulsion Program work being performed
at the Glenn Research Center develops primary propulsion
technologies that can benefit near and mid-term science missions
by reducing cost, mass and/or travel times. The In-Space
Program is working to develop next generation electric propulsion
technologies, including Ion and Hall thrusters. Solar
Sails, which are a form of propellantless propulsion, are
also being developed. Solar Sails rely on the naturally occurring
sunlight for the propulsion energy. Other propulsion technologies
being developed include advanced chemical propulsion and
aerocapture.

Next Evolutionary Xenon Thruster
(NEXT)

NEXT
is one of the projects in the solar electric propulsion
technology area. This project is developing the next
generation ion engine technology and is managed by the
NASA Glenn Research Center. NEXT is a propulsion
system that could revolutionize the way we send science
missions deeper into the solar system. The thruster
uses xenon gas and electrical power to drive future spacecraft.
The goal of NEXT program is to develop an ion thruster
capable of supporting several key NASA missions in the
next decade. The thruster system will enable NASA
to reach destinations in our solar system that cannot be
reached by conventional chemical propulsion.

The major feature of NEXT is a thruster that utilized
design knowledge gained from the ion thruster that successfully
propelled the Deep Space 1 to a flyby of asteroid Braille
and the comet Borrelly. NEXT will have a significant
increase in power compared to that of Deep Space 1's ion
thruster while increasing efficiency and system performance
characteristics. Advanced power processing, xenon propellant
management and thruster gimbal technologies are also being
developed by the team to complete the NEXT ion propulsion
system

The Multi-Mission Earth Entry Vehicle (MMEEV) is a flexible design concept which can be optimized or tailored by any sample return mission, including lunar, asteroid, comet, and planetary (e.g. Mars), to meet that mission’s specific requirements. Based on the Mars Sample Return (MSR) EEV design, which due to planetary protection requirements, is designed to be the most reliable space vehicle ever flown, the MMEEV concept provides a logical foundation by which any sample return mission can build upon in optimizing an EEV design which meets their specific needs By leveraging common design elements, this approach could significantly reduce the risk and associated cost in development across all sample return missions, while also providing significant feed-forward risk reduction in the form of technology development, testing, and even flight experience, for an eventual MSR implementation.

Chemical
propulsion systems have historically been the primary
means for transportation of payloads
in space because they generate the very
large amounts of thrust required to overcome
the effect of Earth's gravity.

Many advanced chemical propellants are being analyzed
and tested to determine their performance and applicability
to in-space propulsion. Chemical rocket systems include
solid, cryogenic liquid, and storable liquid propellants,
as well as hybrid and cold gas rockets.

Aerocapture
is another form of propellantless propulsion. This
technology uses the atmosphere of a destination to achieve
a velocity change necessary to be captured into orbit.

Aerocapture, a flight maneuver that inserts a spacecraft into its desired orbit once it arrives at a planet, is just one of many propulsion technologies being developed by NASA technologists and their partners in industry and academia, led by NASA’s In-Space Propulsion Technology Office at the Glenn Research Center in Cleveland, Ohio. The Center implements the In-Space Propulsion Technology Program on behalf of NASA’s Science Mission Directorate in Washington.

Mission
and systems analysis looks at NASA missions to optimize
trajectories, trip times and payload
delivered. These studies help
determine what technologies are needed to achieve the desired
Science objectives. These studies also compare technologies,
spacecraft concepts and designs to most efficiently goals. The
ISPT project also develops tools for the user community to
assess the applicability of In-Space Technologies.

A joint Mars exploration program between NASA and the European Space Agency (ESA) has set a long term focus on the return of samples from Mars. The current proposed campaign, shown in figure 1, calls for a set of three missions potentially starting in 2018 to 1) Collect a cache of samples, 2) Land, retrieve and launch the samples into Mars orbit, and 3) Rendezvous with the orbiting sample container and return them to Earth for study.